In the steel making industry, it is common to smelt iron ore in a blast furnace to produce hot, molten pig iron. The molten pig iron is then transferred to other areas of the steel mill, such as a basic oxygen furnace, for further processing into steel. In a steel mill, the molten pig iron is transferred by means of transfer vessels such as torpedo or bottle cars.
A torpedo car typically includes an elongated vessel which is rotatable about its longitudinal axis, as disclosed for example in U.S. Pat. No. 3,661,374. An opening is formed in the central portion of the rotatable vessel. Molten metal is poured into the vessel through the opening when the vessel is oriented with the opening in an upward-facing position. The molten metal is discharged from the vessel through the opening when the vessel is rotated about its longitudinal axis. Rotation of the vessel is typically accomplished by a complicated mechanism which requires frequent maintenance.
In a torpedo car, the vessel is mounted between spaced apart railcar trucks thereby allowing the vessel to be transported along rails or tracks. Since the rails usually do not run directly between the blast furnace and the basic oxygen furnace (hereinafter, b.o.f.), the torpedo car must be switched from one set of rails to another. Such shunting increases the time needed to transport the molten metal to the b.o.f. The tracks and the locomotive used to pull the torpedo cars must be frequently maintained.
Typically, the tap hole of a blast furnace is located on or near the bottom of the furnace and a torpedo car must therefore be designed to fit beneath the furnace. Further, large torpedo cars are difficult to rotate and are less stable due to their high center of gravity. Hence, the maximum size of the torpedo cars is limited and many torpedo cars are generally needed to transfer enough molten metal from the furnace to constitute a single charge for the b.o.f.
The known process of transporting molten metal from a blast furnace to a b.o.f. is illustrated schematically in FIG. 7. A transport vehicle transports a full transfer vessel 78, such as a torpedo car, from a first discharging location 71 of a blast furnace 70 to a holding station 80 along a Path 51. The transport vehicle proceeds along a Path 52, picks up an empty transfer vessel 78' and transports it along a Path 53 to the first discharging location 71. The transport vehicle then proceeds along a Path 54, picks up the full vessel 78 and transports it along a Path 55 to a molten metal pouring station 82, where the contents of the transfer vessel 78 are cast into a receiving vessel 83. The first transport vehicle then transports the empty transfer vessel 78 along Path 56 and positions the empty transfer vessel 78 at a second discharging location 71' of the blast furnace 70.
An overhead crane transfers the full receiving vessel 83 from the pouring station 82 to a receiving station 85 of the b.o.f. 87 along a Path 57. The molten metal is typically desulphurized in the receiving vessel 83 at the receiving station 85. The overhead crane proceeds along a Path 58 to an empty receiving vessel 83' which it picks up and transports along Path 59 to the pouring station 82. A disadvantage of this process, aside from its complexity, is the need to build and maintain a pouring station 82. In addition, the transfer of molten metal to a receiving vessel 83 typically results in a 56.degree. C. (100.degree. F.) loss of heat. This heat must later be restored to the molten metal which adds to the production cost. Further, the transfer of molten metal to the receiving vessel 83 results in the release of polluting gases and iron dust into the environment.
Accordingly, it would be highly advantageous to provide an apparatus and a process whereby sufficient molten metal for further processing is transferred from a furnace directly to a single, large capacity vessel. This eliminates the need for transferring the molten metal to a receiving vessel which, in turn, reduces environmental pollution, increases the molten metal charge temperature, and eliminates the cost of building and maintaining a molten metal pouring station. Preferably, the vessel should be simple to construct and easy to operate and maintain. Further, the apparatus should be suitable for use with existing blast furnaces without requiring major structural changes to the furnace. Additionally, the apparatus should be easily adapted for transport by rubber tire or pallet carriers in order to decrease the transport time and eliminate the need for locomotives and tracks to transport the vessel.